Since you've obviously given this careful thought:
(a) How confident are you that this (seemingly obvious now, in the distant aftermath) idea ever even occurred, or was suggested, to Ike?
(b) Assuming he did consider it, are there other considerations besides--that is, in addition to--his dislike of Devers that might have deterred him from adopting the Henkster Hierarchy?
I’m not sure if the idea was ever seriously considered. I tell you what. Read this book.
http://www.history.army.mil/html/books/007/7-1/index.html
The answer is in there. Somewhere. My guess is it never occurred to Ike and was never suggested. Devers’ army came up from the south. He was not in “the club” of the generals who came out of Normandy. The United States was way more political than is widely portrayed. There was no way Bradley was going to give up Patton’s army, and Ike probably never considered it.
PS: The official history of Devers’ command, “Riviera to the Rhine,” was the last volume of the official history to be published. That was in 1993, almost 50 years later, and long after all of the principals had gone to the Big Barracks in the Sky. It was so much longer after the other histories had been published it almost seemed as though the Army didn’t want to publish it all.
Not only was Devers treated like the red headed stepchild during the war, he was effectively sentenced to obscurity afterward.